Means for determining the tectonics and nature of subsurface geology



March 9, 1943., R, 1; LEE 2,313,384

' MEANS FOR DETERMINING THE TECTONICS AND NATURE SUBSURFACE GEOLOGY Filed April 28, 1939 4 Sheets-Sheet 1 TEMPERATURE 2 MID/Cl TOR March 9, 1943. R. E. LEE 2,313,334

MEANS FOR DETERMINING THE 'TECTONICS AND NATURE 0F SUBSURFACE GEOLOGY Filed April 28, 1939 4 sheets -sheet 3 nwucn fo'r/ oberf .5 Lee R. E. LEE 2,313,384

MEANS FOR DETERMINING THE TECTONICS AND NATURE OF SUBSURFACE GEOLOGY M ch 9, 1943-.

Filed April as, 1939 4 Sheets-Sheet 4 lOZ l @obezpz E. Lee

Patented Mar. 9, 1943 S PATEN MEANS FOR DETERMINING THE TECTONICS AND NATURE OF SUBSURFACE GEOLOGY Robert E. Lee, Coleman, 'lex., assignor, by mesne assignments, to Joseph H. Reynolds Application April as, 1939, Serial No. 210,503

5 Claims.

This invention relates to new and useful improvements in means for determining the teetonics. and nature of subsurface geolo y- One object of the invention i to provide an improved method of geophysical survey whereby the tectonics and nature of the subsurface formations may be determined through the medium of an electrical current, either direct or alterbases are provided for accurate calibration to ascertain the resistivity, conductivity and salinity of the formation and thereby accurately determine the structure and nature of said formation. Another object of the invention *is to provide an improved method by which a continuous recrd may be obtained of the nature and tectonics of the formations traversed during the drilling operation, whereby an accurate log may be produced without the necessity of subsequent surveys. i

whereby an accurate log of the underground structure may be produced.

A further object of the invention is to provide an improved apparatus for geophysical explora 'tion, wherein the inherent terrestrial temperature of the formation is determined and also wherein the resistivity, conductivity and salinity of said formation is determined; such infor- A further object of the invention is to provide 7 an improved method whereby the inherent terrestrial temperature of the formations may be ascertained so that said temperatures may be taken into consideration when determining the resistivity, conductivity and salinity of the for- .nating. .mat'ion yielding valuable information as to the An important object of the invention is to prounderground structure. I vide an improved electrical method of geophysi- Still another object of me invention is to procal survey which may be employed either during i an ed im r f h ac e the drilling operation, or subsequent thereto, described, which will enable surveys to be made whereby the nature andstructure of the formaof wells being drilled with either rotary or cable tions in advanc otth rillin t l, or immetools, said apparatus permitting electrical and temperature surveys to be made during the actual drilling operation, or subsequent thereto.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, in which an example of the invention is shown, and wherein: Y v

Figure 1 is an elevation of the apparatus, constructedin "accordance with the invention, for

being shown'inawell bore,

Figure 2 is an enlarged, partial, transverse. sectional view ofthe lower portion of the apps.- ratus, Z L

Figure 3 is anenlarged view, partly in section and partly in elevation,showingthe connection performing the improved methodQsaid apparatus 0 between the swivel and rotating drill stem,

Figure 5 is a horizontal, cross-sectional view,

mations, which assures more accurate informata en on the line 5 of Fi re tion as to the structure of said formation. su e 6 is a hor zontal. c -s ct l V A particular object of the invention is'to protaken on he n 1 Figure vide an improved method, of the character de- Figure is a horizontal, cross-sectional view.

scribed, wherein regional surveys may be made taken 1 the line 1-1 of Figure 4; v

of formations as a bore hole is progressively sur- Figure 8 is a wiringdiagram of the receiving veyed, thereby enabling an operator to deterand measuring circuit and instruments,

mine and locate nonconformities, lensing and Fisure9 is an elevation of the lower portion shore line conditions, such as lenticular sands. f the drill stem and illustrating the general in the subsurface geology. shape of the electrical field when generated into sun another object of the invention is to proto B formation of relatively low ivi y.

vide an improved apparatus adapted to be as- Figure 10 is a view, partly in section and partly sociated with a rotating drilling tool} which is in elevation, of "a slightly modified form of the constructed so that the nature and tectonics of invent n.

the subsurface formations surrounding, or in ad-. l 'igure 11 is an enlargeddetail of the electrical vance of the drilling tool, may be determined, connection at each tool Joint,

.of the derrick legs.

Figure 12 is an elevation of a modified form 01' the invention, illustrating the same lowered in a well bore, and

Figure 13 is an enlarged, transverse, vertical,

" sectionalview of this modified form.

This application is filed as a continuation in part of my copending application filed March 28, 1938, Serial No. 198,546.

In the drawingsthe numeral I designates the floor of a conventional derrick, on which the usual rotary table II is mounted. An angular drive member or kelly I2 extends through the rotary table and is arranged to be rotated thereby, the upper end of said kelly being supported by the usual swivel l3 which is suspended from the top of the derrick (not shown). The lower end of the kelly I2 is connected, by means of a coupling I4, to the drill pipe I5, which pipe extends downwardly through the well bore A. The coupling I4 is, in fact, a tool joint and, as is I6 provided with a. threaded 'bore II, which bore i arranged to receive the lower screw-threaded end of the kelly I2. The pin section I6 of the tool joint is adapted to be threaded into the clearly shown'in Figure 4, includes a pin section socket of the usual tool joint box I8. Thebox 18 is shown as formed integral with the upper end of each section of the drill pipe I5, but if desired said box could be made separately and the i drill pipe threaded into the lower end thereof.

The various sections of the drill pipe are coupled together by means of the tool -joint I and the lowermost section of drill pipe is connected .with an elongate housing I9, wherein the electrical surveying apparatus, as will be hereinafter described, is mounted. The lower end of the housing I9 is provided with an axial screwthreaded socket 20, whereby a suitable drill bit 2|, of any desired construction, may be secured to said housing.

' ity;

ature indicator I. The cable 22 and its leads 26 and 21 house six wires 28,28a, 29, 29a, 30 and 30a. The wires 28 and 28a have connection with the transmitter or generator T, the wires 29 and 23a have connection with the receiver R, while the wires 30 and 30a have connection with the temperature indicator I. 4

The transmitting circuit T includes a suitable source of electricity such as an alternating current generator 3|. It is noted, however, that any source 01' electrical current, either alter-- nating or direct, may be employed. Lead wires -3Ia and 3"), extend from the generator 3I and are arranged to -be connected through a manually operated switch 32 with the wires 28 and 28a which extend through the cable 22. An ammeter 33 is connected in the wire 3Ia and a volt meter 34 i positioned across the circuit, as is clearly shown in Figure 1. is closed, the generator 3I will generate and transmit'electrical current over the wires 28 and 28a, as will be hereinafter explained.

For making an electrical connection between the cable 22, which is stationary, and the rotating drive element or kelly I2, the commutator assembly 25 is provided. This assembly is clearly shown in Figure 3 and includes an annular housing-35, which is formed with a depending collar 35. The collar 36 is internally screw-threaded to receive the upper end of the kelly I2. A commutator disk 31', which is constructed of an insulating material, is mounted within the annular housing so as to be rotatable therewith. This disk has a plurality of concentric contact rings The survey apparatus which is located within the housing I3 is electrically operated and it is necessary that electrical current be'conducted downwardly to this apparatus. Also, it is'necessary that readings or indications be taken at the surface and other lead wires must extend through the drill stem and kelly for this purpose. The lead wires which are necessary for the operation or the device are housed within a suit-able cable 22 which is wound on a reel 23 carried by suitable supports 24, as is clearly shown in Figure 1. 'I'he'supports 2 4 are preferably secured to one One end of the cable 22 is connected to a commutator assembly 25 which is mounted on the upper end of the kelly l2, as will be hereinafter explained. The other end of the cable 22 is connected with a transmitting or generating circuit T, which. is shown schematically in Figure 1. The cable is provided with a branch lead 25 which has connection with a suitable receiver, as will be hereinai'ter explained. A second branch lead 21 extends from the'cable.

38, 39, 40, 4|, 42 and 43 mounted thereon. The contact rings are arranged to be engaged by a plurality of spring-pressed-brushes 33', 39210, ll, 42', and 43', which brushes are mounted within a circular block 44. -The block has its lower portion disposed within the annular housing 35 and is'i'ormed with upwardly extending arms 45 which are secured by means of a clamp 46 to the swivel I3. A short pipe [3 has its upper end connected to the swivel 13, while its lower end is threaded into the collar 36' so as to communicate with the bore thereof, whereby drilling fluid may be circulated downwardly through the swivel, then through the pipe I3 and into the kelly I2.

With the arrangement of the commutator as sembly, the block which carries the springpressed brushes is fixed to the swivel and is nonrotatable.

The contact rings which are carried by the commutator disk are rotatable with the annular housing 35 which is .carried by the upper end of the rotating kelly I2. Since the brushes are in constant engagement with the contact rings, it will be manifest that the electricalconnection betweenthe brushes and the rings will be maintained during rotation of the drive element I2.

The cable 22, which houses the six lead wires, 'as has been explained, is connected to the nonrotatable block 44. The wires 28 and 28a. are connected to the brushes 38' and 33', which brushes engage the outermost rings 38 and 39. The wires 29 and 29a, which lead from the re- .ceiver, are connectedto the brushes lll'v and II.

which brushes are in engagement with the contact rings 40 and :4I. The'wires. 30 'and 33a,

which lead from the temperature indicator 1, are

connected to the innermost brushes 42' and 43',

, which brushes engage the rings 42- and I3.

22 and has connection with a suitable temper- For conducting '-the current downwardly through the kelly I2 and through the drill stem When the switch 32 kelly or and finally to the housing I8, lead wires extend from the rings 38 to 43. Since these wires are,

in effect, a continuation of the six lead wires housed within the cable 22 and branch leads 28 and 21, said wires have been given a corresponding number. Therefore, lead wires 28 and-28a lead downwardly from thecontact rings 38 and 39, lead wires 29 and 29a lead downwardly from the contact rings 46 and H, while the wires 30 and 30a lead downwardly from the rings 42 and 43. As is clearly shown in Figure 3, each of these wires extend through an opening 41 inthe wall of the collar 36 and are then turned downwardly toextend. through the bore me: the kelly I2.

' Q'The wires which extend downwardly through the kelly I 2 are held against the wall of said kelly by a suitable? split ring 18, which ring is con-- structed of a spring metal. The ring is clearly shown in Figure 7 and servesto keep the wires separated from each other and in close proximity with the wall of the bore. For making and continuingthe electrical connection of the wiresthrough the tool joint I l,

the bore of said tool joint is provided with a pair ofcontact members 49 and 56 (Figure 4). The member 49 is in the form of a collar which is dising elements may be disposed within the openings in the plate and around the lead wires to prevent the drilling fluid from passing into the housing Is.

The housing I9 is constructed of'four sections I9a, I9b, I90 and IN. The sections I8a, I91) and I80 are tubular and are coupled together by section I8d is, of course, connected to the section I90 and has its lower end directly connected to posed within the socket of the tool joint box. I8;

A plurality of contact rings BI are mounted in the bore of the collar 49 and the lead wires are connected to these rings. The member 56 is in the form of a block and has a plurality of contact rings on its outer surface, which rings are conthe drill stem. When the tool joint is made up,

the block so is moved into the collar 4a, whereby the contact rings of these two members are'moved into registration and engagement with each other, whereby when the joint is completely made up, an electrical connection is established there-= through.

The lowermost section of the drill pipe 65 is connected into the pin section IE oi the lowermost tool jointId. This pin section is, in turn, threaded into the upper end of the housing Iii, as is clearly shown in Figure 2. A suitable insulating bushing 53, preferably constructed of a non-ferrous insulating material, is interposed between the pin section I6 and said housing, wherev by the housing is insulated from the drill stern I5. A transverse plate 64 is clamped between the end of the pin section I6 and a shoulder 56 formed within the upper end of the housing It and this plate rests on a suitable sealing ring 56, whereby the periphery of the plate is in fluidtight engagement with the wall of the housing. A stufling box 56' extends upwardly from the plate and has the upper end of a tubular conductor 51 extending therethrough. The conductor 51 extends axially through the housing I9 and has its lower end threaded into an opening 58 which is provided in the bottom of said 4 housing. The opening 68 communicates with the bore 2| a of the drill bit 2| and, manifestly,

a drilling fluid, which may be circulated downwardly through the dril1 stem I5. may flow through the conductor I5] and to the bit'2l in order to lubricate the cutting element of said bit. Since the partition 64 has its peripheral portion sealed, it is evident that the drilling fluid cannot pass downwardly into the interior of the housing IS. The wires", 28a, 29, 26a, 30 and 300, which lead from the unit at the surface, pass through suitable openings in the plate 54. whereby the lower ends of 'said leads extend into the interior of the housing I 9. It isnoted that suitable pack- 'nected to the wires passing downwardly through .insulated from the sections I91; and I90.

the drill bit 2i, as has been explained. The entire intermediate section I9b may be constructed of an electrical insulating or non-ferrous material to assure its insulation from the other sec-- tions.

The electrical apparatus, which is housed within the housing I9, has been shown schematically and, as explained, the lead wires from the surface extend downwardly into the interior of the housing. Referring to Figure 2, it will be seen that the wires 28 and 28a, which wires lead from the generator T, are connected to the primary coil 69 of a transformer which is mounted within the upper section I9a of the housing. The purpose of the transformer is to change the low voltage alternating current into a high voltage alternating current. The transformer includes the usual core 60 which is interposed between the primary coil and a secondary coil 6I. A variable condenser 62 is arranged across the secondary circuit of the transformer and said secondary circuit also includes a fixed spark gap 63 and a variable inductance coil 64. If desired, a vacuum tube of suitable construction may be substituted for the spark gap. A coupling coil 65 is connected to a contact 66, which contact is threaded into the wall of the section I911. This latter coil also has connection through a wire 65a with a second contact 67 which is threaded into the third section I of thehousing and, with this arrangement, it will be obvious that the contacts 68 and 61 which are connected to the coupling coil 65, are insulated from each other being -sep arated by the intermediate section I9b which is The contacts 66 and 61 also have connection withthe wire 29 which leads downwardly through the plate 54. It is noted that the upper end of the wire, after passing through the commutator assembly 25, extends through the cable 22 and then through the lead 26 and finally connects to the receiver R.

tends downwardly through the cable 22 and then through the drill stem I6, as explained, and into the interior of the-housing I9. This wire, as is clearly shown in Figure 2, extends downwardly through the sections I9b, I90 and into the interior of thelowermost section I9d of the housing. The wire has connection with a metallic contact 68, which contact ha its outer end exposed to the exterior of the housing. The contact 68 is mounted within a bushing 69, which is constructed of an insulating material, whereby {said contact is insulated from the section I9b.v

The receiver R, which is connected to the lead wires 29 and 29a extending from the contacts The upp 61 and 8, respectively, is schematically shown in Figure 8. The receiver comprisesa square law vacuum tube voltmeter and the lead wires 28 and 29a are connected. to a variable resistance III. A resistance 'H is arranged across the circuit, with a condenser 12 being interposed between the resistances l and II. A vacuum tube 13 is connected in the circuit, being connected in parallel to the above described circuit through a resistance II. A recording milliammeter I is also connected in the circuit, which circuit is supplied with direct current by a battery 16. A bucking battery I1 -is connected across the milliammeter and its circuit includes a variable resistance". The purpose of the variable resistance is to en- 'ablean operator to neutralize the eilects of ter'- restrial magnetism and the electrical phenomena inherent in the region which is being explored,

as will be explained.

From the'foregoing, it will be seen that the lead wires 28 and 28a serve to conduct an electrical current downwardly through the transe former and to the region beingexplored, whereby an electrical field-will be generated in the subsurface formation surrounding the drill stem. The lead wires 29 and 19a serve to operate the receiver R at the surface to indicate the effect of the electrical field which is set up in the for-' which is disposed'within a hermetically sealed annular chamber or tube 80. As explained, the

ator determines this temperature, he can utilize the information to properly calibrate the conductivity or resistivity of the surrounding formatiomas will now be explained.

In practicing the improved method with the apparatus disclosed herein, the bit is first lowered into the bore and the calculations may be made during the drilling operation. When a readingis to be taken, the first reading is that of the temperature indicator 1. This reading is taken while the drill bit is at rest and is not under rotation. ,The indication which is obtained will indicate the inherent terrestrial. temperature and such indication is noted. The temperature of the drilling fluid which is being circulated downwardly through the drill stem and upwardly through the bore outside of said drill stem is then determined. This temperature, as it affects the temperature of the bore adjacent the housing It, will be indicated by the .diirerentialbetween the temperature of the drilling fluid which is introduced into the upper end of the kelly I:

and the temperature of the drilling fluid as it I escapes from the upper end of the bore. By noting this temperature differential, the operator can determine the heat transfer which occurs through the circulating drilling fluid and the formation which it contacts during its circulation. In other words, if the drilling fluid is introduced into the kelly at one temperature and is discharged from the upper end of the well bore a at a higher temperature,' this will indicate to the operator that the highest temperature within the bore is approximately that of thedischarging drilling fluid, and such highest temperature ordinarily isat the bottom of the bore. Thus, the operator can take into consideration the temperature rise or drop in the fluid which is brought about by the circulation of the drilling upper ends of the wires 30 and "a are connected to the circuit or the temperature indicator I, which is diagrammatically shown in Figure i.

This circuit includes a battery I I, or other source of direct current, which battery has its opposite sides connected to the wires 30 and "a. A suitable manual switch I! is connected in the wire 30, while an ammeter O3 is connected in the wire Illa. A voltmeter 84 is arranged across the circult, as illustrated.

It is well known that the resistance of an insulated thermoresistance cell will vary with the temperature of the surrounding" medium and, therefore, if the temperature surrounding the coil is higher, a different resistance is had than if a lower temperature is present around said coil.

According to Ohm's law, the readings of the voltmeter 84 and the ammeter It in the indicating circuit I. which vary with the resistance of the coil 19, will indicate the temperature adjacent said coil. Thus, by observing the ammeter and voltmeter in the circuit 1, it is possible to determine the resistance of the coil II and thereby arrive at the temperature in the well bore adjacent said coil. I l

It is also well known that the temperature of matter affects its electrical conductivity or resistivity. Therefore, in passing an electrical current through a body, its is desirable to know the temperature of that body in order to properly calibrate the conductivityor resistivity thereof.

' For 'this reasomthe provision of the thermore slstance coil I! makes it possible for the operator to know the temperature. within the bore surfluid.

After the indications on the indicator I, and the temperature differential of the circulating fluid, have been noted, the rotary table. II may be rotated to rotate the kelly l2. Such rotation will result in a rotation of the drill stem ltand a rotation of the drill bit 2i, wherebythe drilling operation is performed. It isobvious that the rotation of the drill bit, as it engages the formation to perform the drilling operation, will create a friction which-will result in additional heat at the bottom of the well bore. Such heat which is the result of the friction will, of course, act upon the thermoresistance coil 10 to change the indication or reading on the indicator I. By

noting such change in the indicator reading, and keeping in mind the previous reading, as well as the temperature differential in the circulating fluid, the operator may readily calibrate the inherent terrestrial temperature of the medium or media which is adjacent the drilling bit. There'- fore, as the bit moves downwardly through the various formations traversed by the well bore A. the operator is at all times advised of the inherent terrestrial temperature of said formations as the bit moves therethrough.

To determine the nature of the formation adjacent the housing I, the switch 32 of thegen erator' T is closed so as to connect said generator with the wires a and 28a. when this occurs, an electrical current is conducted to the primary coil" of the transformer, whichis located inthe upper section Ila of the housing a. The transformer acts to increase the voltage to a predetermined degree and a high frequency is obtsined through the medium of the variable condenser 62, spark gap 63 and variable inductance coil 64. It is noted that the setting of the variable inductance is predetermined and is held constant throughout the survey, whether such survey is made during the drilling operation or is made subsequent thereto.

As has been explained, the coupling coil 65 is connected to the electrical contacts 66 and 61, which contacts are mounted or connected with the sections I911 and I90 of the housing, said contacts being separated by the insulated section I9b. Thus, it will be seen thatacurrent of high frequency of predetermined characteristics is propagated and imposed upon the mediasur setting up a field between the section We and the drill stem, the lowermost sections of said stem may be of insulating or non-ferrous material. I I

It is well known that when 'an electric-field is set up within a media, the electric field pattern is dependent upon the character or nature of said media. In other words, if the media is of high resistivity and low conductivity, the field pattern will be as illustrated in Figure 1} with the lines of force extending vertically rather than; radiall outwardly from the bore. If .the media is of a high conductivity and low resistivity, such as a porous formation saturated with salt water,

then thefel'ectri'cfal field pattern will be as shown in Figure 9, Wit'h" thelines of force extending a relatively far distance outwardly from the bore.

-Thus, it will be seen that the field pattern which occurs when the electrical field is formed varies with the particular. formation or strata'whichis adjacent the point of generation.

Referring again to Figure 1 which the field pattern when the neutral zone is surrounded by a media of high resistivity, it will be observed that the electrical lines of force are arranged to engage the metallic contact 68. This contact, as has been explained, isconnected by the lead wire 29:; toxthe receiver R. Consequently, distortion of the lines-of force will impose a change in voltage on the receiver circuit, which distortion will vary as a function thereof. Therefore, when the lines of force are as shown in Figure l, the intensityof the electrical field adjacent the contact 68 is much greater than it is when the field pattern ,is as in Figure 9, with the result that an indicatidn on the milliammeter'IS of the receiver will indicate the distortion of the lines of force or the electrical field pattern. When the field pattern is as inFigure 1, it is obvious that the electrical lines of force, .under certain conditions, will penetrate media below the earth boring tool, and hence surface indica-' illustrates indicator I, is considered along with the particu lar field pattern which is set up, an accurate knowledge of the nature and characteristics of housing I9.

fan, accurate reading on the receiver. cases',-=it would be possible to provide a plurality and conductivity of a particular formation vary.

With the method and apparatus herein described, all of the conditions, which enter into an electrical survey of the formations, are ascertained, whereby an accurate survey is possible. It is noted that thefield pattern is determined directly at the zone being surveyed which rrokes for more accurate information; also the survey may be made while the drilling operation is being performed or, if desired, the survey may be made while the drill bit is inactive and subsequent to the drilling f In Figure 10, a slightly modified form of the 'i-n vcntion is shown. It may be that in some instances, and, under certain conditions, that a single contact 68 would be, insufiicient to provide In such of the contacts 69, which contacts are mounted in the wall of the lowermost section I911 of the Each contact 68 would be connected to an individual receiver (not shown) andsby noting the readings, as affected or controlled. by

. each contact, a more accurate indication of the distortion 'of the field pattern could be obtained. Thus, it will be seen that the invention is not to be limited to the use of a single contact 68 as any de'sirednumbcr may be employed,

As before stated, the methodmay be per-- formed. either during the drilling operation anding unit, herein described, may be'operated in a bore hole which has been previously drilled by means 0f a cable instead of a drill stem, the units of the circuit being encased within the cable,

insulated from each other and from the cable.

In Figures 1 to 11, the invention has been shown and described .as applied to a drill stem and bit, whereby surveys may be made during or subsequent to the drilling operation. However, it is'noted that, if desired, the housing I9 may be a separate unit and may be' lowered through a pre-drilled bore hole on a wire line or cable. Such an arrangement is clearly shown in Figures 12 and 18, wherein the housing I9 and its associate parts areof substantially the same construction. However, in this form, the lower end of the housing is closed by a bull plug I00 which is threaded into the axial opening 20 in the bottom of said housing. The upper end of the housing has a. cable socket IOI threaded thereinto and a cable I02 has its lower end secured within the socket in the'usual manner. A packing gland I03 surrounds the cable and is located within the upper end of the socket for packing off around said cable. In this form, the vertical pipe or conductor 51, as well as the transverse partition 54, are omitted and the various lead wires 28, 28a,

tions may be made relative to the strata to be encountered as drilling proceeds. Manifestly,

when the field pattern is known. this indicatesthe pcnetration'of the electrical lines of force.

radially through the strata or formations, whereby the nature and tectonicsof said formations may be determined. When the inherent terrestrial temperature, as previously determined by I means of thc thermoresistance coil 19 and the 29, 290,30 and 30a are housec within the cable ment are mounted within the truck. The operation of this form is exactly the same as the form, wherein the apparatus is connected in the drill stem. The cable supported unit involves less time in making the surveys for it may be lowered and raised much more quickly. In both instances, an electrical field is set up in the formation adjacent the unit and the measurement of the distortion of said field is taken at the field, rather than at a point remote therefrom.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made,

within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. An apparatus for geophysical exploration including, a housing adapted to be connected in a drill stem, means carried by the housing for setting up an electrical field within the media surrounding said housing, a receiver at the surface, and means mounted on the housing effected by the electrical field and connected with the receiver for indicating the physical distortion of the electrical field pattern as caused by the nature and characteristics of the formation.

2. An apparatus for geophysical exploration including, a housing adapted to be connected in a drill stem, means for conducting an electrical current to the housing to set up an electrical field within the media surrounding said housing,

- a receiver at the surface, means on the housing current to the housing to set up an electrical field within the media surrounding said housing,

a receiver at the surface, means on the housing effected by the electrical field and connected with the receiver for indicating the physical distortion of the electrical field pattern as caused bythe nature and characteristics of the formation, a thermoresistance coil carried by the housing, and

electrical means connected with said coil for indicating changes in its resistance as caused by.

temperature changes in the bore.

4. An apparatus for geophysical exploration including, a housing adapted to be connected in a drill stem, means carried by the housing for setting up an electrical field within the media of the field as affected by the nature and charac 1 teristics of the formation.

5. An apparatus for geophysical exploration including a housing adapted to be connected in a drill stem, means carried by the housing for setting up an electrical field within the media surrounding said housing, means for conducting an electrical current to the last named means for actuating the same, means mounted on the housing adjacent the media in which the electrical field is set up for determining the plxvslcal dis-' tortion of the electrical field pattern, indicatin means at the surface connected with the determining means for visibly indicating the distortion of the field as aifected by the nature and characteristicsof the formation, means mounted on the housing for determining the. terrestrial temperature of the formation, and means at the surface for indicating such temperature as de-.

termined by the last named means.

ROBERT E. LEE; 

